As many as 700 million people worldwide suffer from onychomycosis or toenail fungal infections. There are many systemic, topical and herbal treatments available to treat this disease but none are truly efficacious and several have severe potential side effects. A need exists for a better cure for this widespread disease.
Optical and laser treatment of toenail fungus has been known for many years. In particular, UV light in the 100-400 nm range has proven to be able to inactivate many pathogens including the ones responsible for onychomycosis in non-thermal dosages. Unfortunately UV light has difficulty penetrating the toenail and can cause side effects in the dermis. UV light is not considered to be a successful treatment modality despite a great deal of research.
U.S. Pat. No. 6,723,090, issued Apr. 20, 2004 to Altshuler et al., U.S. Pat. No. 7,220,254, issued May 22, 2007 to Altshuler et al., US Publication No. 2006/0212098, published Sep. 21, 2006 to Demetriou et al., Non-patent publication “Laser treatment for toenail fungus”, Proc. of SPIE Vol. 7161 published 2009 by Harris et al. and others have proposed using infrared radiation to thermally inactivate toenail fungus. Infrared radiation penetrates the toenail much better than UV and it has been shown that the fungus can be inactivated by raising the temperature of the pathogen to about 50° C. The problem associated with this method is that achieving the inactivation temperature in the nail bed risks damaging the surrounding dermal tissue, especially the matrix where the nail actually grows. In addition this prior art allows the use of infrared radiation with high hemoglobin absorption. Hemoglobin absorbing wavelengths can coagulate capillaries in the proximal fold and permanently damage the toenail.
U.S. Pat. No. 6,723,090, issued Apr. 20, 2004 to Altshuler et al., U.S. Pat. No. 7,220,254, issued May 22, 2007 to Altshuler et al. propose to use a cooling modality to protect the toenail during infrared laser irradiation to target the nail bed and he suggests that a pulsed laser may be superior to a continuous one.
US Publication No. 2006/0212098, published Sep. 21, 2006 to Demetriou et al. suggests the use of pulsed cryogen cooling, which is also described in U.S. Pat. No. 5,814,040, issued Sep. 29, 1998 to Nelson et al., to protect the toe from excessive heating and to use the process of selective photothermolysis, which is disclosed in non-patent publication “Selective Photothermolysis: Precise Microsurgery by Selective Absorption of Pulsed Radiation”, published on Science, 220:524-527, 1983 by Anderson et al., to choose the correct pulse length to match the thermal properties of the fungus itself. Methods taught respectively in U.S. Pat. Nos. '090, '254 to Altshuler et al. and US Publication '098 by Demetriou et al. all require relatively high target temperatures that can damage the matrix and teach to cool only the surrounding tissue. The above-mentioned methods may cause permanent damage to sensitive areas.
U.S. Pat. No. 6,090,788, issued Jul. 18, 2000 to Lurie teaches that light-absorbing substances may be considered to induce and enhance selective photothermal damage. The problem and shortcoming with this method is the difficulty in getting the substance infused to the proper areas and the high temperatures required to inactivate the microbe. Damage to the surrounding tissue is likely to happen by using this method.
Non-patent publication “Method for disruption and re-canalization of atherosclerotic plaques in coronary vessels with photothermal bubbles generated around gold nanoparticles”, published on Lasers Surg Med, 2009. 41(3): p. 240-7 by Lukianova-Hleb, E. Y., A. G. Mrochek, and D. O. proposes a non-thermal mechanical and localized removal of plaque tissue with photothermal microbubbles—PTMB to re-canalize occluded arteries without collateral damage using gold nano particles—GNP. It also teaches that users can induce non-thermal damage to locally remove unwanted tissue by producing PTMB using GNP as a catalyzer. This method however has not been proven to be efficient enough to be practical in removing large volumes of plaque buildup.
Non-patent publication “Laser surgery of port wine stains using local vacuum pressure: Changes in skin morphology and optical properties (Part I)”, published on Lasers Surg Med, 2007. 39(2): p. 108-17 by Childers et al. proposes that mild vacuum pressures applied to the skin surface causes changes in morphology and its optical properties. These changes may be used for more efficient photothermolysis of small Port Wine Stain blood vessels. The vacuum suggested by Childers et al. however works primarily on blood vessels in the dermis.